generate changelog from git log
Add tests for getChangesFromGit
rewrite changelog extraction logic from git log
add nextVersion field
move getters just after class constructor
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/main/java/ru/yandex/jenkins/plugins/debuilder/GitCommitHelper.java
update git-client, all tests now pass
make custom versioning optional
merge 2 optional blocks
Merge pull request #10 from itIGO/master

Generate changelog from git log